Gear checking fixture



Jan- 9, 1945 G. lR. cHlTwooD 2,367,004

I GEAR CHECKING FIXTURE K Filed Feb. 2a, 1944 2 sheets-sheet 1 Bg gli (Ittornegf Smoentor Jan. 9, 12455?, A G. R. cHlTwooD 3674004 GEAR CHECKING FIXTUREV Filed Feb. 2s, 1944 2 sheets-sheet 2 v gli Ww f @limi @,JIUMIL HHHTVI Uhm@ Snnentor l l Gttornegs- Patented Jani 9, 1945 ERATEN ff-ioF Flffc-E i GClaims. (Cl. .3S-179.5) I

' l-Tlnsinventionfrlatesto yamgage orxtureor checking gears, lparticularly to .check thewpitch fdiametergthe" concentrcityand vparallelism with :'Inimoder'n"practicevwheregears o'f anytype zare used.onfnaircraftfengines, or'in other rela- '.tionsiwhe're fextrem'ef accuracy is necessary,v itf is iiesirable "to heckrfeach rgear'l'to `determine that the teeth thereof are properly shaped rand that :thefigear L is accurateeandf precise in 'fall respects.

v This.' cannot be 'donenvisuallwan'd Where Smallinaccuracies are present and are diilcultifto dise A'coverfby"any-ordinary means, itisf'de'sirable to Ehavesome vkindof a fdevice or means `whereby ithefcenterfof the .xturefwwith theiindicatcrs .fre- :moved/zand noggearron thegpfost.

Figure 3 isa perspective viewcofrthe vmaster .;=gear.

5 Y.fl'igure .i4 Misra @perspective tview tof :.the ranvl :awhiclfr/iszpivotedinzthehead.

l Eigurei:,isfsaltopfplanzviexrny of; thesrxtur-eryvith parts broken away and shown in sectionnhetter 4:toillustrate iithe .constructiomzand :with athe'liny:lofolicators"-renfmved. f

"'Figure-'G is:anrend'fviewiofrthez'xtnrezwviththe indicatorsrremcved l x-lnererringf.texthe drawings, tzthefxtureaas @a whole is indicated at l. The xturef'comprises tithe. gear may he corrected to bringit to theneclfessar-ydegreeof accuracy. "The-'fixture or device :iff the "present invention was ldesigned to Acheck La ygear and 'determine the three lmosty likely esourcesof error, thatl is, (1) to check the "pitch 'fadiame'ter;"(2) tocheck the-'"conc'entricity of'the '.'teeth and their lparallelism withi the bore of' the ;gear; rand.(3) .to check'the lead or helixo'f the -jgeariteeth The flxture of the inventionis lprovided with threefgages or indicators, one for each oef rthe r.three mentioned'sources of inaccuracy-to vhe checked. "Two of'these-'gages areA mounted konta 'housing f or block in which there is slidably -fmounted'a *shaft having a'hea'd thereon and the third-indicator `is "mounted on `,the head.y The 1"headhasrpivotedftheretoan anvil and a movement of thisanvil is communicated to the indi- 'cator--mounted on the head. The other twoin- 'fdicatorslhavetheirfprobes in contact AWith-.the head, one lbeing inv contact With the upper .sur- "fa'ce tohave communicated rto vthe ,probe the.. ro-

"tarymotion of,the`-head, and' theother indicator f ."'has itsjp'rbegcontacting.with'the frontface of the"` head to' receive any.v amount .of axial.v movef ment of'the headand shaft. vI'Ihe gear to be testedgismounted cin!- a'postatthe front of the "xture, `and". byf having the indicators previously '.jsetto zeroLby thelusenia master gage, the exact #i4 lamountfondegree of,.errorwin a gear can. be read Zdirectlyfrom.thegages f orhany gear applied to 'fthepost.' AThe, reading `onthe dial ,ofthe kgages which departs eitherway frorniz'erowill 'begthe -amountof'errorfinthelgear. l 50A v Onrthedrawings: f y l i Figure 1 lis a. perspective 'viewL of .thefxtura z-.showingnargear-f-to bechecked in positionon the ppost..

"eachziside of thefhousingzare securejdztov the'zbase v rzran'd overlapatheflangesrandf rigidly? holdgithe .izhousing-SG in position. *lIfit isfdesired'lkto adj-ust "'25 iThebase 1:2 iswprovidedl '-with1an cpeningr lid-fiat lfitsendfsandin fthisropen-ing v"aj-husliing l lr6 is xref'cived, `A"In:theirlcushing'thereis receivedfithe lower enlarged end 'f I-Bf of=afpostff20awhich :proj ectscupewardlyfinr'front off the' housing. "lThe po'st120 prefy35 thereinfandi in'ythisfopening thereis secured@ the "bearing Ei311. fInf the: hearing =30 there is=sl-idably mounted the-shaft 32one-en`d-of -Whichfis reduced f as at 34 ande, coil springi36 "tsaroundthereduced partSL AApla-te '-381`isfsecured toi theyrear The opposite endfcf theffshaft 132 fislformedinto Ja'PheafCISSL 1' Th'ef'headhhasftheiforwardly extend- .ingf'r'ibs'i 56feach-f r`which isprovided with al cen- 1ftr'a1l'1opening for thepurpose of wreceivinga pin'f58.

ICBetween the ribs" there -s'mounted'theanvil 60 from'thfbaseoff thehea'd' ibas-is indicated bythe space at 64 and the front end parts of the anvil have projecting tapered parts 66 as is best shown in Figures 4 and 5. The .tapered parts have the tip cut out to V formation as shown at 68, and there is also a deepening cut positioned at the bottom of the V-shaped formation 58. The sides of the V 68 form an angle of 90. Between the end parts 66 and positioned in the the `V-shaped formations, there is a; pin 12 which has a central groove 14 around which there is wound one end of a wire 16, the other end of which is bent and is fastened by means of a screw 18 to the anvil 60. The wire 16 holds the pin 12 in the V formation 68,

The head 54 is provided with a post au on which v there is mounted an indicator or gage 82 having a movable probe or finger 84 which contacts with the anvil 60 at the end of the cut 10 of the V- shaped groove 68.

The housing 6 has a post 88 on which there is mounted a second indicator 90, the probe or finger 82 of which rests on top of the head 54 as is best shown in Figure 1.

The housing 6 has aithird indicator 94 mounted on a bracket 96 secured to the hou-sing 6. The probe 98 of the indicator 94 rests on the front face of the housing'at the surface indicated at |00 in Figure 5.

These indicators or gages 82, 90 and B4 may be of any suitable type and are provided with a dial and pointer and a suitable meter mechanism. The gages or indicators and their probes are conventionally indicated, and per se form no part of the invention.

The initial operation for the machine is to take a master gage |02 as shown in Figure 3 and place it on the post 20 with the groove |04 facing the head 54 and pin 12. The groove |04 in the master gage |02 is an exact reproduction of the correct space between two adjacent teeth of the gear to be gaged. This groove |04 is also in exact parallelism with the centerline of the bore |06 of the master gear |02. To put the master gear |02 in position on the post 20, the operator will pull forward on the handle 48 t0 withdraw the head 54 and shaft 32 rearwardly and compress the spring 36. The master gear |02 is now yplaced on the post 20 and the operator then gradually releases the handle 48 to, cause the pin 12 to fit in the groove |04. The pitch circle of the gear will intersect the axis of the pin 12. The gages 82, 90 and 94 are now al1 adjusted so that their pointers read Zero for the reason that this is the reading desired for an accurate gear. The handle 48 is then again operated to enable the operator to remove the gage |02, and a gear to be checked |08 is then placed on the post 20. The handle is again gradually released so that the pin 12 ts in the space between adjacent teeth on the gear.

1. Should there be any lack of parallelism between the teeth and the bore of the gear, i. e., if the groove be deeper at one end, this will be shown by a slight tilting of the anvil 60 through its pin 58. The pin 12, of course, will communicate this out-of-parallelism to the anvil and the movement of the anvil will be transmitted to the probe 84 of the gage 82 so that themovement of the anvil will be registered on the gage 82.

2. If the gear being checked is a spur gear, then the gage or indicator 90 should register zero because there is no lead to the gear. If the gear is other than a spur gear, the pin 12 as` it fits in the groove between adjacent teeth will cause the head 54 to rotate through an angle in accordance with lthe inclination of the teeth or in accordancewith iii the lead and this turning of the head will move the probe 92 to cause the dial and pointer of the indicator 90 to register the lead angle. By a suitable graduation of the dial the lead angle can be read directly or the amount of error determined.

3. The indicator 94 will indicate the amount of error in the pitch diameter. If this diameter be inaccurate, the pin will be positioned more or less deep in the groove and this changein depth over thel normal position will cause the head 54 to advance to or recede from the gear and this axial movement of the head will be communicated to the indicator 94 by itsprobe 98 and the reading on the dial will indicate the error in the pitch diameter. The indicator 94 also checks the runout ,of the gear, i. e., the concentricity of the gear teeth pitch circle with the bore of the gear.

'Any one of the above errors may affect more than one indicator, but the operator, with a little experience, can determine the amount of any error in a gear by interpreting the various indicator readings.

A latch ||0 is pivoted at ||2 to the plate 33. The purpose of this latch is to lock the head 54-through the intermediary of the shaft 32 and the nut M -and prevent the spring 36 from forcing the head toward the mounting post 20 when the handle 48 is released. The latch H0 is hand operated.

A pin ||2 is secured in the block 6 and limits the angular or rotary movement of the head 54.

claim:

l. In a gear checking fixture, a base, a housing and a post supported on the base, said post adapted to receive the gear to be checked, a shaft turnably supported in the housing, a head on the end of said shaft, means constantly urging f ie shaft out of the housing and the head away from the housing and toward the post, an anvil pivoted to the head, a pinmounted on the anvil and projecting away therefrom, said pin being adapted to be engaged in the space between adjacent teeth of the gear on the post, a plurality of indicators mounted on the housing and having operative Contact with the head and being operated from the head by the movement thereof, said indicators indicating the lead of the gear and the amount of the runout thereof, an indicator mounted on the head and having operative contact with the anvil and being operated from the anvil by the movement thereof, said indicator indicating the misalignment of the gear teeth with reference to the axis of the gear, the movement of the anvil and the head caused by any error in the gear being registered on the indicators.

2. The invention of claim l, said indicator measuring the lead oi the gear being in operative contact withthe top face of the head to communicate to the indicator the rotary motion of the head caused by an error in the gear.

3. The invention of claim 1, said indicator measuring the runout of the gear being in operative contact with the front face of the head to communicate to the indicator the axial movement of the head caused by an error in the gear.

4. In a gear checking xture, a base, a housing 'and a post supported on ther base, said post adapted to receive the gear to be checked, a shaft turnably supported in the housing, a head on the end of said shaft, means constantly urging the shaft out of the housing and the head away from the housing and toward the post, means on the head and projecting away therefrom and being adapted to be engaged in the space between afljacent teeth of the gear on the post, an indicator mounted on the housingv and being operated ,n from the head by the rotary movement thereof,

the movement of said head caused by an error in the gear being registered on the indicator, said indicator indicating the lead -of the gear. v

' 5. In a-gear checking fixture, a base, a hous-y ing and a post supported on the base, said post adapted to lreceive the gear to be checked,a shaft turnably supported in the housing, a head on Athe end of said shaft, means constantly urging the shaft out of the housing and the head away'frorn the housing and toward the post,means on the head and projecting away therefrom and beingr adapted to, be engaged in the space between adjacent teeth ofthe gear on thev post, van indicator mounted `on'the headfand being operated from being registered on the indicator, said indicator` indicating the misalignment of the gear teeth y teeth of the gear on the post, an indicator mounted on the housing and being operated from said means by the movement thereof, the movef ment of said head caused by an error-in the gear the front face of the head by the axial movement thereof, the movement of the head caused by an error'in the gear being registered on theindicator,

said indicator indicating the amount of the runout of the gear.

GEORGE R. CI-IITWOOD. 

